Rhododendron plant named ‘HoldenRhodo212’

ABSTRACT

A new cultivar of hybrid  Rhododendron  plant named ‘HoldenRhodo212’ that is characterized by its resistance to root rot caused by  Phytophthora cinnamomi , its old hardiness at least in U.S.D.A Zone 5, its flowers that are fuchsia in color, its adaptability to open field conditions in Northeast Ohio, and its compact form that has been observed after 8 years.

Botanical classification: Rhododendron hybrida.

Cultivar designation: ‘HoldenRhodo212’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar of Rhododendron plant of hybrid origin, botanically known as Rhododendron ‘HoldenRhodo212’ and will be referred to hereafter by its cultivar name, ‘HoldenRhodo212’. ‘HoldenRhodo212’ is a new cultivar of Rhododendron shrub grown for use as a landscape plant.

The new cultivar arose from a controlled breeding program by the Inventor in Madison, Ohio and Kirtland, Ohio with the objective of developing new cultivars of Rhododendron with resistance to root rot, greater sun adaptability, and compact growth habits.

The new cultivar was derived from a cross made by the Inventor in spring of 1996 between Rhododendron ‘Rio’ (not patented) as the female parent, and Rhododendron ‘Rocket’ (not patented) as the male parent. The Inventor selected ‘HoldenRhodo212’ as a single unique plant amongst the seedlings that resulted from the above cross in spring of 1998.

Asexual propagation of the new cultivar was first accomplished by semi-hardwood stem cuttings in Madison, Ohio, in 2010 under the direction the Inventor. Asexual propagation by semi-hardwood stem cuttings and tissue culture utilizing meristematic tissue has determined that the characteristics of the new cultivar are stable and are reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

The following traits have been repeatedly observed and represent the characteristics ‘HoldenRhodo212’. These attributes in combination distinguish ‘HoldenRhodo212’ as a new and distinct cultivar of Rhododendron.

-   -   1. ‘HoldenRhodo212’ exhibits resistance to root rot caused by         Phytophthora cinnamomi.     -   2. ‘HoldenRhodo212’ exhibits cold hardiness at least in U.S.D.A         Zone 5.     -   3. ‘HoldenRhodo212’ exhibits flowers that are fuchsia in color.     -   4. ‘HoldenRhodo212’ exhibits adaptability to open field         conditions in Northeast Ohio.     -   5. ‘HoldenRhodo212’ exhibits a compact form that has been         observed after 8 years.

The female parent of ‘HoldenRhodo212’ differs from ‘HoldenRhodo212’ in having pink flowers with a yellow center and in being susceptible to root rot. The male parent of ‘HoldenRhodo212’ differs from ‘HoldenRhodo212’ in having flowers that are rose pink in color and bullate leaves. ‘HoldenRhodo212’ can also be most closely compared to the Rhododendron cultivars ‘Besse Howells’ (not patented) and ‘Haaga’ (not patented). ‘Besse Howells’ is similar to ‘HoldenRhodo212’ in being cold hardy in U.S.D.A. Zone 5 and in growth rate and habit. ‘Besse Howells’ differs from ‘HoldenRhodo212’ in being susceptible to root rot and in having frilled flowers that are darker in color. ‘Haaga’ is similar to ‘HoldenRhodo212’ in being cold hardy to U.S.D.A. Zone 5 and in having resistance to root rot when grown in open field conditions with low root rot disease pressure. ‘Haaga’ differs from ‘HoldenRhodo212’ in being highly susceptible to root rot when grown under commercial growing conditions and in having lighter pink colored flowers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying color photographs illustrate the overall appearance and distinct characteristics of the new Rhododendron. The plant in the photograph is 2.5 years in age as grown outdoors in Kirtland, Ohio.

The photograph in FIG. 1 provides a side view of ‘HoldenRhodo212’ in bloom.

The photograph in FIG. 2 provides a close-up view of the inflorescences of ‘HoldenRhodo212’.

The colors in the photographs are as close as possible with the digital photography and printing techniques utilized and the color codes in the detailed botanical description accurately describe the new Rhododendron.

DETAILED BOTANICAL DESCRIPTION OF THE PLANT

The following is a detailed description of 8-year-old plants of the new cultivar as grown outdoors in an evaluation garden in Madison, Ohio. The phenotype of the new cultivar may vary with variations in environmental, climatic, and cultural conditions, as it has not been tested under all possible environmental conditions. The color determination is in accordance with The 1995 Colour Chart of The Royal Horticultural Society, London, England, except where general color terms of ordinary dictionary significance are used.

-   General characteristics:     -   -   Blooming period.—2 to 3 weeks, depending on weather,             typically commencing in late May in Ohio.         -   Plant type.—Evergreen shrub.         -   Plant habit.—Rounded and densely branched.         -   Height and spread.—Reaches 1.1 m in height and 1.2 m in             width after 8 years in the landscape.         -   Cold hardiness.—Plant is hardy to at least U.S.D.A. Zone 5a,             flower buds are resistant to cold damage when exposed to             temperatures of −20 F, possibly colder.         -   Diseases and pests.—Observed to be resistant to root rot             caused by Phytophthora cinnamomi under field conditions,             typical of evergreen Rhododendrons; lace bugs (Stephanitis             takeyai) can establish on leaves under full sun conditions,             no other susceptibility or resistance to other pests or             diseases has been observed.         -   Root description.—Fibrous, near 165A in color.         -   Propagation.—Tissue culture (preferred) or semi-hardwood             stem cuttings.         -   Growth rate.—Moderate.         -   Root development.—4 to 8 weeks for root initiation and 2             years to produce a young plant from a rooted cutting. -   Stem description:     -   -   Shape.—Round.         -   Stem color.—Young; 144A, maturing; late season semi-hardwood             stems a blend of 144A and 144B, as the wood lignifies             becoming 6A, mature stems; 183B, older stems; 177B and 177C.         -   Stem size.—Main stem; forks at 10 cm in length, 1.5 cm in             diameter, lateral branches above fork; 98 cm in length, 2.9             cm in width, current season growth; an average of 6.7 cm in             length and 3 mm in width.         -   Stem surface.—Young; slightly rough to the touch, lightly             covered in wooly pubescent hairs, becoming less hairy as the             stems mature.         -   Stem aspect.—Held outward from main stem.         -   Stem strength.—Strong.         -   Branching.—Densely branched. -   Foliage description:     -   -   Leaf shape.—Elliptic to obovate.         -   Leaf division.—Simple.         -   Leaf base.—Obtuse to rounded.         -   Leaf apex.—Primarily acute.         -   Leaf venation.—Pinnate, upper surface; 138B in color,             lateral vein colors ranging from 138B to matching the leaf             color, lower surface; midrib and lateral veins 145D and 148C             in color.         -   Leaf margins.—Entire.         -   Leaf attachment.—Petiolate.         -   Leaf arrangement.—Alternate, leaf clusters whorled at             terminal shoot apex.         -   Leaf internode length.—Up to 1.2 cm.         -   Leaf orientation.—Held mostly upright, some slightly             downward.         -   Leaf aspect.—Held mostly flat though can be cupped downward             at shoot apex.         -   Leaf surface.—Upper surface: smooth, glabrous, slightly             shiny with a thick texture, lower surface: smooth, dull,             glabrous.         -   Leaf color.—Young leaves upper surface; 144A with a dark             yellow overtone, young leaves lower surface; 144D in color,             mature leaves upper surface; a blend of 137C and 138AB,             mature leaves lower surface; a blend of 145A and 145B, no             change in color in fall.         -   Leaf size.—Ranging from 3.3 to 12.5 cm in length and 2.2 to             4.7 cm in width.         -   Leaf quantity.—An average of 5 leaves per new season shoot             and previous season shoot, leaves retained 2 to 3 years.         -   Petioles.—Average of 1.4 mm in length and 2 mm in diameter,             near 150B in color, smooth to lightly pubescent surface. -   Flower description:     -   -   Inflorescence type.—Umbellate raceme.         -   Lastingness of flowers.—Total duration of bloom 2 to 3             weeks, flowers petals are self-cleaning.         -   Inflorescence size.—Average of 9.1 cm in height and 9 cm in             width.         -   Flower size.—An average of 3.2 cm in depth and 4.5 cm in             diameter.         -   Flower fragrance.—None to very faint.         -   Flower shape.—Broad, tubular funnel.         -   Flower number.—Average of 12 per inflorescence.         -   Flower aspect.—Outward.         -   Flower bud.—Obovate in shape, 1; occasionally 2 per terminal             shoot whorl, round in cross-section, pointed apex, color;             151B with interior scales closer to 145B, scale edges are             near 168B.         -   Flower attachment.—Pedicellate.         -   Petal number.—5.         -   Petal shape.—Ovate to elliptic.         -   Petal color.—Upper and lower surface when opening (balloon             stage); 67B, upper surface when fully open; 75D with 75A and             75B (most prominent near apex), lower surface when fully             open; 73B, margins 75B.         -   Petal surface.—Waxy, glabrous, and smooth on both upper and             lower surfaces.         -   Petal margins.—Entire, slightly undulate.         -   Petal apex.—Acuminate and notched.         -   Petal base.—Fused.         -   Petal size.—An average of 3.5 cm in length and 2.2 cm in             width.         -   Sepal number.—5 highly reduced sepals.         -   Sepal shape.—Narrowly deltate.         -   Sepal margin.—Entire.         -   Sepal size.—Average of 1 mm in length and 2 mm in width.         -   Sepal surface.—Pubescent to smooth on upper and lower             surface.         -   Sepal apex.—Abruptly rounded.         -   Sepal base.—Fused.         -   Sepal color.—Both surfaces 145B on both immature and mature             sepals.         -   Peduncle.—An average of 2.7 cm in height and 4 mm in             diameter, near 144B in color, strong, surface slightly to             not pubescent.         -   Pedicels.—An average of 2.9 cm in length and 2 mm in             diameter, smooth surface, near 144B in color, strong,             surface with minimal to no hairs. -   Reproductive organs:     -   -   Gynoecium.—Pistil; 1, stigmas; round in shape, 57A in color,             1 to 2 mm in diameter, style; average 3.6 cm in length,             curved, color 58A near stigma fading to 58D near ovary,             ovary; 152A in color.         -   Androecium.—Stamens; 10, anthers; oblong to elliptical in             shape, 2.5 mm long and 1.5 mm wide, 75A in color; pollen             154D in color and moderate in quantity.         -   Fruit/seeds.—Dehiscent, 5 to 6 valved capsules, size is             dependent on pollination, up to 2.3 cm and 1 cm in length             and width, color; interior 161B, exterior a mix of 165A,             199C, 200C. 

It is claimed:
 1. A new and distinct cultivar of Rhododendron plant named ‘HoldenRhodo212’ as herein illustrated and described. 